Twilio-media-stream-save-audio-file NPM

Twilio Media Stream Save Audio File

This codebase provides a simple Node.js library class that makes it easy to save Twilio media streams to a local audio file in wav format.

Purpose

I was playing around with the Twilio Media Streams and wanted to easily save the phone call to a local wav file after the call completed. I did a quick Google search and found someone on StackOverflow (Inspired by user @tdeo: https://stackoverflow.com/questions/58439005/is-there-any-way-to-save-mulaw-audio-stream-from-twilio-in-a-file) who had provided code snippet for writing a Mulaw header for a WAV-file compatible with twilio format.

To make this a bit simpler I have taken this code snippet and converted it into a Node.js (CommonJS) class library for easier usage.

If you need to save a Twilio Media Stream phone call to a local audio file when the call completes then this library should help you.

Example Usage

const TwilioMediaStreamSaveAudioFile = require("twilio-media-stream-save-audio-file");

const mediaStreamSaver = new TwilioMediaStreamSaveAudioFile({
  saveLocation: __dirname,
  saveFilename: "my-twilio-media-stream-output",
  onSaved: () => console.log("File was saved!"),
});

wss.on("connection", (ws) => {
  console.log("New connection initiated!");

  ws.on("message", (message) => {
    const msg = JSON.parse(message);
    switch (msg.event) {
      case "connected":
        console.log("A new call has connected");
        break;
      case "start":
        console.log(`Starting media stream...`);
        mediaStreamSaver.twilioStreamStart();
        break;
      case "media":
        console.log("Receiving audio...");
        mediaStreamSaver.twilioStreamMedia(msg.media.payload);
        break;
      case "stop":
        console.log("Call has ended");
        mediaStreamSaver.twilioStreamStop();
        break;
      default:
        break;
    }
  });
});

Options

When you instantiate the library you can pass in the following options. They are not required and all optional.

saveLocation - (Optional) Defaults to the local dir using __dirname. You can set any path you wish. Make sure path exists.
saveFilename - (Optional) Defaults to the current date timestamp using Date.now(). You can set any filename you wish.
onSaved - (Optional) This is a optional callback function that you can provide if you want to be notified when the audio wav file has been saved.

Notes

Inside the connected websocket message event make sure to call each of the corresponding methods for the incoming Twilio Media Stream message events:
Twilio Media Stream Message Event: start
- mediaStreamSaver.twilioStreamStart()
Twilio Media Stream Message Event: media
- mediaStreamSaver.twilioStreamMedia(twilioMediaPayload)
Twilio Media Stream Message Event: stop
- mediaStreamSaver.twilioStreamStop()

For getting started on how Twilio media streams work, check out Twilio.